THE RECENT CRINOIDS OP AUSTRALIA— CLARK. 7 77 



their neighbours laterally ; there is considerably more flattening 

 than in the species of Tropiometra, as the plates are deeper dorso- 

 ventrally ; the four brachials following the tirst syzygial pair are 

 obloug and very sliort; the following are triangular, soon becom- 

 ing aboufc as long as broad. 



The proximal pinnules are large and strongly prismatic; P^ is 

 the largest and longest, and is composed of from eight to ten 

 segments, of which the third and fourth are the largest and 

 longest; the size, stoutness, and length of the pinnules giadually 

 decreases to Pg or P^ ; the distal pinnules are not much longer 

 than Pg. 



Bell's Antedonhideiis is the same thing as Lamarck's Comatula 

 adeonce ; in the best specimen obtained by the "Alert" the cirri 

 are about xx, 21 ; the bidentate appearance is caused by the 

 moving back of the transverse ridge so far that it is near the 

 proximal end of the segments, while the distal dorsal edge of the 

 segments has become prominent, so that there are in effect two 

 transverse z'idges, appearing as two small spines in lateral view. 



Pi is the longest, considerably stiffened ; P2 is similar, but 

 slightly shorter ; Pg is similar, but slightly shorter than Pg ; the 

 distal ends of the segments of these lower pinnules tend to become 

 slightly prominent. 



The figure of this species given in the " Alert " Report is very 

 misleading, but a good (photographic) illustration of it is given 

 by Doderlein in the reference cited. 



OLIGOMETRA THETIDIS (//. L. Clark). 



Oligometra thetidis, 1909, H. L. Clark, Mem. Aust. Alus., vol. 4, 

 Part 11, p. 522, pi. xlvii., figs. 1-3 (off Wollongong, 

 55-56 FMS.). 

 Description.--! happened to be in Cambridge, Massachusetts, 

 when Dr. H. L. Clark received the collection of Echinoderms 

 brought together by H.M.C.S. "Thetis," and he most courteously 

 permitted me to examine the specimens of Crinoids therein con- 

 tained. This new Oligometra is a form of rather exceptional 

 interest, and I availed myself of the opportunity of drawing up a 

 careful description of it. This description is somewhat more 

 detailed than that published by Dr. Clark, and follows more 

 closely the terminology and form in present use, so that it may 

 not be out of place to incorporate it here. 



Centrodorsal low-hemispherical, a rather large polar area bare> 

 the cirrus sockets arranged in two irregular closely crowded rows- 

 Cirri xv-xx, 15 (rarely 14, 16, or 17), short and stout ; first 

 segment very short, second somewhat longer, becoming on the 



